Displaying publications 81 - 100 of 162 in total

Abstract:
Sort:
  1. Zaini MF, Razak IA, Anis MZ, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2019 Jan 01;75(Pt 1):58-63.
    PMID: 30713734 DOI: 10.1107/S2056989018017371
    The asymmetric unit of the title halogenated chalcone derivative, C15H10BrFO, contains two independent mol-ecules, both adopting an s-cis configuration with respect to the C=O and C=C bonds. In the crystal, centrosymmetrically related mol-ecules are linked into dimers via inter-molecular hydrogen bonds, forming rings with R 1 2(6), R 2 2(10) and R 2 2(14) graph-set motifs. The dimers are further connected by C-H⋯O inter-actions into chains parallel to [001]. A Hirshfeld surface analysis suggests that the most significant contribution to the crystal packing is by H⋯H contacts (26.3%). Calculations performed on the optimized structure obtained using density functional theory (DFT) at B3LYP with the 6-311 G++(d,p) basis set reveal that the HOMO-LUMO energy gap is 4.12 eV, indicating the suitability of this crystal for optoelectronic and biological applications. The nucleophilic and electrophilic binding site regions are elucidated using the mol-ecular electrostatic potential (MEP).
  2. Thanigaimani K, Khalib NC, Razak IA, Lavanya P, Balasubramani K
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jun 01;69(Pt 6):o968-9.
    PMID: 23795125 DOI: 10.1107/S1600536813013883
    The benzoic acid mol-ecule of the title adduct, C10H11N5·C7H6O2, is approximately planar, with a dihedral angle of 7.2 (3)° between the carb-oxy-lic acid group and the benzene ring. In the triazine mol-ecule, the plane of the triazine ring makes a dihedral angle of 28.85 (9)° with that of the adjacent benzene ring. In the crystal, the two components are linked by N-H⋯O and O-H⋯N hydrogen bonds with an R 2 (2)(8) motif, thus generating a 1 + 1 unit of triazine and benzoic acid mol-ecules. The acid-base units are further connected by N-H⋯N hydrogen bonds with R 2 (2)(8) motifs, forming a supra-molecular ribbon along [101]. The crystal structure also features weak π-π [centroid-centroid distances = 3.7638 (12) and 3.6008 (12) Å] and C-H⋯π inter-actions.
  3. Thanigaimani K, Farhadikoutenaei A, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Dec 01;68(Pt 12):o3319-20.
    PMID: 23476163 DOI: 10.1107/S1600536812045291
    In the title salt, C6H9N2(+)·C2F3O2(-), the F atoms of the anion are disordered over two sets of sites, with refined occupancies in a ratio of 0.505 (17):0.495 (17). In the crystal, cations and anions are linked via N-H⋯O hydrogen bonds, forming R2(2)(8) ring motifs. The ionic units are linked into a two-dimensional network parallel to (100) by N-H⋯O and weak C-H⋯O hydrogen bonds. The crystal structure is further stabilized by weak C-H⋯F hydrogen bonds, resulting in a three-dimensional network.
  4. Zaini MF, Razak IA, Khairul WM, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2019 May 01;75(Pt 5):685-689.
    PMID: 31110811 DOI: 10.1107/S2056989019005243
    The title compound, C23H15NO3, adopts an s-cis conformation with respect to the ethyl-ene C=C and carbonyl C=O double bonds in the enone unit. The mol-ecule is significantly twisted with a dihedral angle of 48.63 (14)° between the anthracene ring system and the benzene ring. In the crystal, mol-ecules are linked into inversion dimers with an R 2 2(10) graph-set motif via pairs of C-H⋯O hydrogen bonds. The inter-molecular inter-actions were analysed and qu-anti-fied by Hirshfeld surface analysis. The mol-ecular structure was optimized and a small HOMO-LUMO energy gap of 2.55 eV was obtained using the DFT method at the B3LYP/6-311 G++(d,p) level of theory. This value is in close agreement with the experimental value of 2.52 eV obtained from the UV-vis analysis. The crystal used was a two-component merohedral twin with a refined ratio of 0.1996 (16):0.8004 (16).
  5. Zaini MF, Razak IA, Khairul WM, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2020 Mar 01;76(Pt 3):387-391.
    PMID: 32148881 DOI: 10.1107/S2056989020002054
    A new conjugated carbazole chalcone compound, (E)-3-[4-(9,9a-di-hydro-8aH-carbazol-9-yl)phen-yl]-1-(4-nitro-phen-yl)prop-2-en-1-one (CPNC), C27H18N2O3, was synthesized using a Claisen-Schmidt condensation reaction. CPNC crystallizes in the monoclinic non-centrosymmetric space group Cc and adopts an s-cis conformation with respect to the ethyl-enic double bonds (C=O and C=C). The crystal packing features C-H⋯O and C-H⋯π inter-actions whose percentage contribution was qu-anti-fied by Hirshfeld surface analysis. Quantum chemistry calculations including geometrical optimization and mol-ecular electrostatic potential (MEP) were analysed by density functional theory (DFT) with a B3LYP/6-311 G++(d,p) basis set.
  6. Ahmad MS, Abuzar MA, Razak IA, Rahman SA, Borromeo GL
    Eur J Dent Educ, 2017 Nov;21(4):e29-e38.
    PMID: 27273317 DOI: 10.1111/eje.12211
    Poor oral health has been associated with compromised general health and quality of life. To promote comprehensive patient management, the role of medical professionals in oral health maintenance is compelling, thus indicating the need for educational preparation in this area of practice. This study aimed to determine the extent of training in oral health in Malaysian and Australian medical schools. An audio-recorded semi-structured phone interview involving Academic Programme Directors in Malaysian (n = 9, response rate=81.8%) and Australian (n = 7, response rate = 35.0%) medical schools was conducted during the 2014/2015 and 2014 academic years, respectively. Qualitative data was analysed via thematic analysis, involving coding and grouping into emerging themes. Quantitative data were measured for frequencies. It was found that medical schools in Malaysia and Australia offered limited teaching of various oral health-related components that were mostly integrated throughout the curriculum, in the absence of structured learning objectives, teaching methodologies and assessment approaches. Barriers to providing oral health education included having insufficient expertise and overloaded curriculum. As medical educators demonstrated support for oral health education, collaboration amongst various stakeholders is integral to developing a well-structured curriculum and practice guidelines on oral health management involving medical professionals.
  7. Purushothaman M, Thanigaimani K, Arshad S, Silambarasan S, Razak IA, Ali KM
    Acta Crystallogr Sect E Struct Rep Online, 2014 Jul 1;70(Pt 7):o812-3.
    PMID: 25161592 DOI: 10.1107/S1600536814014354
    In the title compound, C14H12ClN5, the di-hydro-pyridine ring adopts a shallow boat conformation. The dihedral angle between the plane of this ring and that of the chloro-benzene ring is 69.15 (15)°. In the crystal, mol-ecules are linked by N-H⋯N and N-H⋯Cl hydrogen bonds, generating (001) sheets.
  8. Edison B, Balasubramani K, Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2014 Aug 1;70(Pt 8):o857-8.
    PMID: 25249908 DOI: 10.1107/S1600536814015220
    In the title mol-ecular salt, C4H6ClN4 (+)·C5H7O4 (-), the cation is essentially planar, with a maximum deviation of 0.037 (1) Å for all non-H atoms. The anions are self-assembled through O-H⋯O hydrogen bonds, forming a supra-molecular zigzag chain with graph-set notation C(8). In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms of the anion via a pair of N-H⋯O hydrogen bonds with an R 2 (2)(8) ring motif. This motif further self-organizes through N-H⋯O and O-H⋯O hydrogen bonds, generating an array of six hydrogen bonds, the rings having graph-set notation R 3 (2)(8), R 2 (2)(8), R 4 (2)(8), R 2 (2)(8) and R 3 (2)(8). In addition, another type of R 2 (2)(8) motif is formed by inversion-related pyrimidinium cations via N-H⋯N hydrogen bonds, forming a two-dimensional network parallel to (101).
  9. Hariono M, Wahab HA, Tan ML, Rosli MM, Razak IA
    PMID: 24764997 DOI: 10.1107/S1600536814001986
    In the title compound, C19H17N5S, the dihedral angles between the purine ring system (r.m.s. deviation = 0.009 Å) and the S-bound and methyl-ene-bound phenyl rings are 74.67 (8) and 71.28 (7)°, respectively. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds generate R 2 (2)(8) loops. C-H⋯N inter-actions link the dimers into (100) sheets.
  10. Yeong KY, Ali MA, Choon TS, Rosli MM, Razak IA
    PMID: 24046597 DOI: 10.1107/S1600536813014177
    In the title compound, C28H27FN4O3·H2O, the benzimidazole ring system is essentially planar with a maximum deviation of 0.028 (1) Å. It makes dihedral angles of 47.59 (5) and 60.31 (5)°, respectively, with the pyridine and benzene rings, which make a dihedral angle of 22.58 (6)° with each other. The pyrrolidine ring shows an envelope conformation with one of the methyl-ene C atoms as the flap. In the crystal, the components are connected into a tape along the b-axis direction through O-H⋯O and O-H⋯N hydrogen bonds and a π-π inter-action between the pyridine and benzene rings [centroid-centroid distance of 3.685 (8) Å]. The tapes are further linked into layers parallel to the ab plane by C-H⋯O and C-H⋯F inter-actions.
  11. Yusof MS, Razali NR, Arshad S, Rahman AA, Razak IA
    PMID: 24046599 DOI: 10.1107/S1600536813014268
    In the title mol-ecule, C23H22N2OS, the di-phenyl-acetyl and ethyl-benzene groups adopt a trans-cis conformation, respectively, with respect to the S atom across the (S=)C-N bonds. This conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond and a weak C-H⋯S hydrogen bond. The ethyl-substituted benzene ring forms dihedral angles of 87.53 (15) and 73.94 (15)° with the phenyl rings. In the crystal, N-H⋯O hydrogen bonds link mol-ecules into chains along [100]. A weak C-H⋯π inter-action is also observed.
  12. Turton BJ, Thomson WM, Foster Page LA, Saub RB, Razak IA
    Asia Pac J Public Health, 2015 Mar;27(2):NP2339-49.
    PMID: 24097924 DOI: 10.1177/1010539513497786
    This study aimed to determine the impact of dental caries in terms of Oral Health-Related Quality of Life (OHRQoL) for Cambodian children. The Child Perceptions Questionnaires (CPQ) were cross-culturally adapted and validated for the Cambodian population using a sample of 430 Cambodian children. The participants had a high caries burden, with a mean number of decayed-missing-and-filled deciduous tooth surfaces (dmfs) of 8.8 (SD = 11.1) and a mean DMFS of 3.7 (SD = 5.5) for the permanent dentition. Two in 5 children had at least one pulpally involved tooth. There was a significant difference in mean CPQ8-10 and CPQ11-14 scores by caries experience and by global item response for the respective age-groups, with those in the more severe caries categories scoring higher. Similar gradients were apparent with the CPQ11-14 in the 8- to 10-year age-group. The differences in OHRQoL scores by caries experience demonstrate the construct validity of the CPQ11-14 for the 8- to 14-year age-group.
  13. Yusof MS, Razali NR, Arshad S, Rahman AA, Razak IA
    PMID: 24109341 DOI: 10.1107/S1600536813018680
    The title mol-ecule, C22H17F3N2OS, adopts a trans-cis conformation with respect to the positions of the carbonyl and tri-fluoro-methyl-benzene groups against the thio-carbonyl group across the C-N bonds. The mol-ecular structure is stabilized by an intra-molecular N-H⋯O hydrogen bond with an S(6) ring motif. The tri-fluoro-methyl-substituted benzene ring forms dihedral angles of 66.05 (9) and 47.19 (9)° with the terminal phenyl rings and is twisted from the O=C-N-(C=S)-N carbonyl-thio-urea plane [maximum deviation = 0.0535 (12) Å], making a dihedral angle of 63.59 (8)°. In the crystal, N-H⋯O and C-H⋯F hydrogen bonds link the mol-ecules into a layer parallel to the bc plane. A C-H⋯π inter-action is also observed.
  14. Yusof MS, Razali NR, Arshad S, Rahman AA, Razak IA
    PMID: 23795124 DOI: 10.1107/S1600536813013354
    In the title compound, C25H26N2OS, the diethyl-substituted benzene ring forms dihedral angles of 67.38 (9) and 55.32 (9)° with the terminal benzene rings. The mol-ecule adopts a trans-cis conformation with respect to the orientations of the di-phenyl-methane and 1,3-di-ethyl-benzene groups with respect to the S atom across the C-N bonds. This conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond, which generates an S(6) ring. In the crystal, pairs of N-H⋯S hydrogen bonds link the mol-ecules into inversion dimers, forming R 2 (2)(6) loops. The dimer linkage is reinforced by a pair of C-H⋯S hydrogen bonds, which generate R 2 (2)(8) loops. Weak C-H⋯π and π-π [centroid-centroid seperation = 3.8821 (10) Å] inter-actions also occur in the crystal structure.
  15. Yeong KY, Ali MA, Choon TS, Rosli MM, Razak IA
    PMID: 23795062 DOI: 10.1107/S1600536813012440
    In the title compound, C24H23N3O2, the benzimidazole ring system makes dihedral angles of 7.28 (5) and 67.17 (5)°, respectively, with the planes of the benzene and phenyl rings, which in turn make a dihedral angle of 69.77 (6)°. In the crystal, mol-ecules are connected by C-H⋯N and C-H⋯O inter-actions, forming a layer parallel to the bc plane. A π-π inter-action, with a centroid-centroid distance of 3.656 (1) Å, is observed in the layer.
  16. Ali MA, Manogaran E, Choon TS, Rosli MM, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 May 1;69(Pt 5):o746-7.
    PMID: 23723896 DOI: 10.1107/S1600536813009987
    The asymmetric unit of the title compound, C29H24FNO5·0.5CH3OH, contains two independent mol-ecules and a one methanol solvent mol-ecule. The methanol mol-ecule is O-H⋯O hydrogen bonded to one of the independent mol-ecules. The pyrrolidine rings in both mol-ecules adopt half-chair conformations, while the cyclo-pentane rings within the indane groups are in flattened envelope conformations, with the spiro C atoms forming the flaps. The benzene rings of the indane ring systems form a dihedral angle of 35.06 (7)° in one independent mol-ecule and 31.16 (8)° in the other. The fluoro-substituted benzene ring forms dihedral angles of 65.35 (6) and 85.87 (7)° with the indane group benzene rings in one mol-ecule, and 72.78 (8) and 77.27 (8)° in the other. In each mol-ecule, a weak intra-molecular C-H⋯O hydrogen bond forms an S(6) ring motif. In the crystal, weak C-H⋯O, C-H⋯N and C-H⋯F hydrogen bonds link the mol-ecules into a three-dimensional network.
  17. Wei AC, Ali MA, Choon TS, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Oct 1;68(Pt 10):o2907-8.
    PMID: 23125700 DOI: 10.1107/S1600536812037993
    In the title compound, C(27)H(20)BrNO(3), two intra-molecular C-H⋯O hydrogen bonds both form S(6) rings. The pyrrolidine ring adopts a twisted conformation about the C-C bond bearing the indane ring systems. The other two five-membered rings within the indane systems are in shallow envelope conformations, with the spiro C atoms as the flap atoms. The mean plane of the pyrrolidine ring [maximum deviation = 0.275 (1) Å] makes dihedral angles of 65.25 (7), 78.33 (6) and 75.25 (6)° with the bromo-substituted benzene ring and the mean planes of the mono- and dioxo-substituted indane rings, respectively. In the crystal, mol-ecules are linked by C-H⋯O and C-H⋯N hydrogen bonds into a three-dimensional network. In addition, C-H⋯π inter-actions are observed.
  18. Fadzillah SM, Ngaini Z, Hussain H, Razak IA, Asik SI
    Acta Crystallogr Sect E Struct Rep Online, 2012 Oct 1;68(Pt 10):o2911-2.
    PMID: 23125703 DOI: 10.1107/S1600536812038020
    In the title compound, C(29)H(40)O(3), the enone moiety adopts an s-cis conformation. The dihedral angle between the benzene rings is 4.33 (5)° The least-squares mean line through the tetra-decyl side chain forms a dihedral angle of 83.99 (7)° with the normal to the attached benzene ring. In the crystal, O-H⋯O and C-H⋯O hydrogen bonds involving the keto and the hy-droxy O atoms form ribbons along [-41-1]. The crystal structure also features C-H⋯π inter-actions.
  19. Fadzillah SM, Ngaini Z, Hussain H, Razak IA, Asik SI
    Acta Crystallogr Sect E Struct Rep Online, 2012 Oct 1;68(Pt 10):o2909.
    PMID: 23125701 DOI: 10.1107/S1600536812038007
    In the title compound, C(21)H(24)O(3), the enone moiety adopts an s-cis conformation and the dihedral angle between the benzene rings is 12.89 (6)°. The hex-yloxy tail adopts an extended conformation. In the crystal, inversion dimers are linked by pairs of O-H⋯O hydrogen bonds and pairs of C-H⋯O inter-actions, forming two R(2) (2)(7) and one R(2) (2)(10) loops. The dimers are then arranged into sheets lying parallel to (201) and weak C-H⋯π inter-actions consolidate the packing.
  20. Yoon YK, Ali MA, Choon TS, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Oct 1;68(Pt 10):o2967-8.
    PMID: 23125749 DOI: 10.1107/S1600536812039268
    The asymmetric unit of the title compound, C(27)H(32)N(4)O(4)·H(2)O, contains two independent benzimidazole-5-carboxyl-ate mol-ecules and two water mol-ecules. In both main mol-ecules, the pyrrolidine rings are in an envelope conformation with a methyl-ene C atom as the flap. The morpholine rings adopt chair conformations. Both benzimidazole rings are essentially planar, with maximum deviations of 0.008 (1) Å, and form dihedral angles of 37.65 (6) and 45.44 (6)° with the benzene rings. In one mol-ecule, an intra-molecular C-H⋯O hydrogen bond forms an S(7) ring motif. In the crystal, O-H⋯O and O-H⋯N hydrogen bonds connect pairs of main mol-ecules and pairs of water mol-ecules into two independent centrosymmetric four-compoment aggregates. These aggregates are connect by C-H⋯O hydrogen bonds leading to the formation of a three-dimensional network, which is stabilized by C-H⋯π interactions.
Filters
Contact Us

Please provide feedback to Administrator ([email protected])

External Links